Organic reactants for atomic layer deposition

ABSTRACT

A method for selectively depositing a metal oxide film is disclosed. In particular, the method comprises pulsing a metal or semi-metal precursor onto the substrate and pulsing an organic reactant onto the substrate. A reaction between the metal or semi-metal precursor and the organic reactant selectively forms a metal oxide film on either a dielectric layer or a metal layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation and claims priority to U.S. patentapplication Ser. No. 15/205,827 filed Jul. 8, 2016 titled ORGANICREACTANTS FOR ATOMIC LAYER DEPOSITION, the disclosure of which is herebyincorporated by reference in its entirety.

FIELD OF INVENTION

The present disclosure generally relates to processes for manufacturingelectronic devices. More particularly, the disclosure relates toselectively forming films through cyclic processes such as ALD orsequential/cyclic CVD. Specifically, the disclosure discloses methods toselectively form ALD or sequential/cyclic CVD films with organicreactants.

BACKGROUND OF THE DISCLOSURE

Water (H₂O) has been often used for forming oxides in atomic layerdeposition (ALD) processes. Water is a polar molecule due to its loneelectron pair. Water is also reactive with many metal halides, whichmakes it a candidate for some ALD oxide processes. When used as areactant at low temperatures, however, water has displayed someundesirable behavior.

Most notably, the presence of water as a reactant increases the time tosufficiently purge the tool during an ALD deposition cycle.Specifically, at low temperatures, water tends to stick to varioussurfaces, including substrates and tools with hydrophilic materials. Thesticking of water may make it difficult to purge water from the systemand it may cause loss of selectivity if water-based processes areapplied on selective deposition schemes. In addition, the nature ofwater may oxidize some of the surfaces present on the substrate, whichin some instances is not desirable.

Prior approaches have described using carboxylic acids for ALD of somemetal oxides. However, these have not enabled selective deposition.

As a result, a method for ALD formation of a film that displaysefficient purging and effective modification of the surface is desired.

SUMMARY OF THE DISCLOSURE

In accordance with at least one embodiment of the invention, a method ofselectively forming a metal oxide is disclosed. The method comprises:providing a substrate comprising a dielectric layer and a layercomprising metal for processing in a reaction chamber; exposing thesubstrate to a metal or semi-metal precursor; exposing the substrate toa purging gas and/or a vacuum; exposing the substrate to an organicreactant; and exposing the substrate to a purging gas and/or the vacuum;wherein a reaction between the metal or semi-metal precursor and theorganic reactant selectively forms a metal oxide layer on either thedielectric layer or layer comprising metal. In some embodiments themethod of selectively forming a metal oxide comprises a cyclic processusing a metal or semi-metal precursor and an organic reactant. In someembodiments the method of selectively forming a metal oxide using ametal or semi-metal precursor and an organic reactant comprises an ALDprocess. In some embodiments the method of selectively forming a metaloxide process using a metal or semi-metal precursor and an organicreactant comprises a cyclic or sequential CVD process using a metal orsemi-metal precursor and an organic reactant. In some embodimentsutilizing the cyclic or sequential CVD process, the metal or semi-metalprecursor is partly decomposing on the surface. In some embodimentsutilizing the cyclic or sequential CVD process, gas-phase reactions ofthe metal or semi-metal precursor and the organic reactant aresubstantially avoided. In accordance with exemplary aspects of theseembodiments, the selective formation of the metal oxide layer occurswith use of an etchant before and/or after the formation of the metaloxide layer.

For purposes of summarizing the invention and the advantages achievedover the prior art, certain objects and advantages of the invention havebeen described herein above. Of course, it is to be understood that notnecessarily all such objects or advantages may be achieved in accordancewith any particular embodiment of the invention. Thus, for example,those skilled in the art will recognize that the invention may beembodied or carried out in a manner that achieves or optimizes oneadvantage or group of advantages as taught or suggested herein withoutnecessarily achieving other objects or advantages as may be taught orsuggested herein.

All of these embodiments are intended to be within the scope of theinvention herein disclosed. These and other embodiments will becomereadily apparent to those skilled in the art from the following detaileddescription of certain embodiments having reference to the attachedfigures, the invention not being limited to any particular embodiment(s)disclosed.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

These and other features, aspects, and advantages of the inventiondisclosed herein are described below with reference to the drawings ofcertain embodiments, which are intended to illustrate and not to limitthe invention.

FIG. 1 is a cross-sectional view of a semiconductor device in accordancewith at least one embodiment of the invention.

FIG. 2 is a cross-sectional view of a semiconductor device in accordancewith at least one embodiment of the invention.

FIG. 3 is a cross-sectional view of a semiconductor device in accordancewith at least one embodiment of the invention.

FIG. 4 is a flow chart of a method in accordance with at least oneembodiment of the invention.

FIG. 5 is a flow chart of a method in accordance with at least oneembodiment of the invention.

It will be appreciated that elements in the figures are illustrated forsimplicity and clarity and have not necessarily been drawn to scale. Forexample, the dimensions of some of the elements in the figures may beexaggerated relative to other elements to help improve understanding ofillustrated embodiments of the present disclosure.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Although certain embodiments and examples are disclosed below, it willbe understood by those in the art that the invention extends beyond thespecifically disclosed embodiments and/or uses of the invention andobvious modifications and equivalents thereof. Thus, it is intended thatthe scope of the invention disclosed should not be limited by theparticular disclosed embodiments described below.

For selective deposition processes, efficient purging is desirable.Efficient purging may allow for selectivity to take place, as thechemical vapor deposition (CVD) type of gas phase reactions aresignificantly reduced or absent. Additionally, it is generally desirablefor selectivity to have surfaces present with only desired reactivitytowards the deposition chemistry. For example, for some surfaces noreaction with the precursors (or reactants) is desired, and for othersurfaces quick and complete reactions with the precursors (or reactants)are desired. If not present naturally, surfaces may be modified toexhibit the desired reactivity. For example, some surfaces can betreated to slow down the rate or completely inhibit a certain type ofreaction. Surface modifications may be employed when using precursors(or reactants) with undesired reactivity towards a surface present inthe system.

When using water as a reactant, the above goal of efficient purging isdifficult to achieve. Water molecules are said to be polar because theyexhibit an external dipole moment. This causes water to stick easily onsurfaces. If water is used in selective deposition schemes, surfacemodifications may be used to passivate the surfaces against water. Oneexample of such a passivation may include fluorinated or highly methylcovered surfaces, exhibiting high water contact angle. Water contactangle is a measure of the surface energy towards water. Surfaces withhigh water contact angle are typically passive against water.Additionally, the nature of water makes achieving only the right kind ofsurface reactivity more difficult, possibly resulting in a desire forsurface modifications to protect a formed material, for example.Especially at temperature ranges of 100-150° C., water may prove to beproblematic to remove at time scales suitable for production, due to theextended periods of time used to fully purge the water from the systemand all the surfaces. Such temperatures may be encountered in many partsof a film deposition tool, outside the film deposition region.

Organic reactants, such as formic acid (HCOOH) or other carboxylicacids, may prove to be a better choice for ALD processes due to theirproperties. Specifically, organic reactants are not generally polarsubstances that stick to surfaces. In addition, organic reactants have adifferent nature when compared to water. Specifically, HCOOH may be ableto produce reductive reactions. Additionally, organic reactants such asHCOOH begin decomposing at elevated temperatures and do not liberate H₂Oat 100-150° C.

In some embodiments, the organic reactant is a vapor phase organicreactant that may demonstrate thermal stability within a range ofprocess temperatures. For example, the vapor phase organic reactant maybe thermally stable across a desired range of process temperatures suchthat growth-disturbing condensable phases do not form on the substrateand/or the vapor phase organic reactant does not generate harmful levelsof impurities on the substrate surface through thermal decomposition. Insome embodiments, the vapor phase organic reactant may exhibitsufficient vapor pressure such that a desired quantity of chemicalmolecules is present in the gas phase near the substrate surface toenable the reduction reactions.

In some embodiments, a vapor phase organic reactant may be selectedbased on its ability to decompose into two or more reactive components,at least one of which can react with the surface.

In some embodiments, the vapor phase organic reactant may compriseformic acid. In some embodiments, the vapor phase organic reactant maycomprise acetic acid (CH₃COOH) and/or propanoic acid (CH₃CH₂COOH). Insome embodiments, the (e.g., vapor phase) organic reactant may includean alcohol. In some embodiments, the (e.g., vapor phase) organicreactant may include an aldehyde. In some embodiments, the (e.g., vaporphase) organic reactant may have at least one functional group selectedfrom the group consisting of alcohol (—OH), aldehyde (—CHO), andcarboxylic acid (—COOH).

Without being limited by any particular theory or mode of operation, theprocess for depositing metal oxide films selectively using organicreactants may also reduce the metal or metal oxide surfaces present onthe substrate. For example, the carboxylic acid may reduce oxidizedcopper such that the oxidized copper may be restored to its elementalstate. In some embodiments, the organic reactant, when used as oxygensource, may keep the metal surface as elemental metal or metallic orconductive state.

Organic reactants containing at least one alcohol group may bepreferably selected from the group consisting of primary alcohols,secondary alcohols, tertiary alcohols, polyhydroxy alcohols, cyclicalcohols, aromatic alcohols, and other derivatives of alcohols.

Preferred primary alcohols have an -OH group attached to a carbon atom,which may be bonded to another carbon atom, in particular primaryalcohols, according to the general formula (I):

R¹—OH   (I)

wherein R¹ is a linear or branched C₁-C₂₀ alkyl or alkenyl groups,preferably methyl, ethyl, propyl, butyl, pentyl or hexyl groups.Examples of preferred primary alcohols include methanol, ethanol,propanol, butanol, 2-methyl propanol and 2-methyl butanol.

Preferred secondary alcohols have an —OH group attached to a carbon atomthat is bonded to two other carbon atoms. In particular, preferredsecondary alcohols have the general formula (II):

wherein each R¹ is selected independently from the group of linear orbranched C₁-C₂₀ alkyl and alkenyl groups, preferably methyl, ethyl,propyl, butyl, pentyl or hexyl groups. Examples of preferred secondaryalcohols include 2-propanol and 2-butanol.

Preferred tertiary alcohols have an —OH group attached to a carbon atomthat is bonded to three other carbon atoms. In particular, preferredtertiary alcohols have the general formula (III):

wherein each R¹ is selected independently from the group of linear orbranched C₁-C₂₀ alkyl and alkenyl groups, preferably methyl, ethyl,propyl, butyl, pentyl or hexyl groups. An example of a preferredtertiary alcohol is tert-butanol.

Preferred polyhydroxy alcohols, such as diols and triols, have primary,secondary and/or tertiary alcohol groups as described above. Examples ofpreferred polyhydroxy alcohol are ethylene glycol and glycerol.

Preferred cyclic alcohols have an —OH group attached to at least onecarbon atom which is part of a ring of 1 to 10, more preferably 5-6carbon atoms.

Preferred aromatic alcohols have at least one —OH group attached eitherto a benzene ring or to a carbon atom in a side chain.

Preferred reactants containing at least one aldehyde group (—CHO) areselected from the group consisting of compounds having the generalformula (V), alkanedial compounds having the general formula (VI), andother derivatives of aldehydes.

Thus, in one embodiment preferred reactants are aldehydes having thegeneral formula (V):

R³—CHO   (V)

wherein R³ is selected from the group consisting of hydrogen and linearor branched C₁-C₂₀ alkyl and alkenyl groups, preferably methyl, ethyl,propyl, butyl, pentyl or hexyl groups. More preferably, R³ is selectedfrom the group consisting of methyl or ethyl groups. Examples ofpreferred compounds according to formula (V) are formaldehyde,acetaldehyde and butyraldehyde.

In another embodiment preferred reactants are aldehydes having thegeneral formula (VI):

OHC—R⁴—CHO   (VI)

wherein R⁴ is a linear or branched C₁-C₂₀ saturated or unsaturatedhydrocarbon. Alternatively, the aldehyde groups may be directly bondedto each other (R⁴ is null).

Organic reactants containing at least one —COOH group are preferablyselected from the group consisting of compounds of the general formula(VII), polycarboxylic acids, and other derivatives of carboxylic acids.

Thus, in one embodiment, preferred organic reactants may be carboxylicacids having the general formula (VII):

R⁵—COOH   (VII)

wherein R⁵ is hydrogen or linear or branched C₁-C₂₀ alkyl or alkenylgroup, preferably methyl, ethyl, propyl, butyl, pentyl or hexyl, morepreferably methyl or ethyl groups. In some embodiments, R⁵ is a linearor branched C₁-C₃ alkyl or alkenyl group. Examples of preferredcompounds according to formula (VII) are formic acid, propanoic acid andacetic acid, most preferably formic acid (HCOOH).

In some embodiments, the organic reactant demonstrates desired vaporpressure such that the organic reactant may be volatized without heatingthe organic reactant. In some embodiments, such an organic reactant maycomprise only one carboxyl group (—COOH).

In some embodiments, the organic reactant may be heated to volatize theorganic reactant prior to delivering the volatized organic reactant tothe substrate surface. In some embodiments, such an organic reactant maycomprise a dicarboxylic acid, including an oxalic acid.

In some embodiments, the organic reactant may comprise less than about15 weight % water (H₂O). In some embodiments, the organic reactant maycomprise less than about 5 weight % water, less than about 2 weight % orless than about 1 weight %. For example, the organic reactant maycomprise less than about 0.5, less than about 0.1, or less than about0.05 weight % water. In some embodiments, the organic reactant may notcomprise metal. In some embodiments, the organic reactant may compriseonly carbon, hydrogen, and oxygen.

As described herein, an organic reactant may decompose into two or morereactive components during the deposition. For example, some of thecarboxylic acid delivered to a reaction space may decompose into carbonmonoxide (CO) and hydrogen gas (H₂) during the deposition process, suchthat one or more of the carbon monoxide (CO) and hydrogen gas (H₂) mayhelp keep metal or metallic surfaces in its original state, i.e.,prevent oxidation of the metal or metallic surfaces, or reduce them toelemental or metallic state. In this way, a substrate surface may beexposed to hydrogen gas (H₂) even though no hydrogen gas (H₂) isactively provided into the reaction space from an external source.

In some embodiments, the organic reactant may be stored in a liquidphase and subsequently volatized prior to being delivered to thesubstrate surface. In some embodiments, the organic reactant may be invapor phase in the reaction space, such that the reaction space issubstantially free of any liquid phase reactants. For example, theorganic reactant may be in liquid phase during storage and may besubsequently volatized prior to delivery into a reaction chamber, suchthat only or substantially only organic reactant in the vapor phase ispresent within the reaction chamber.

In some embodiments, an organic reactant may be stored in a gas bubblerand can be supplied to the reaction chamber from the gas bubbler. Insome embodiments, the organic reactant may be stored in a gas bubbler ataround room temperature (e.g., from about 20° C. to about 25° C.). Forexample, the organic reactant gas may be pulsed into the reactionchamber from the gas bubbler during a cycle of the deposition process.In some embodiments, a mass flow rate of the organic reactant may becontrolled by controlling the extent to which a valve for delivering theorganic reactant into the reactor chamber is kept open (e.g., a needlevalve). For example, a mass flow rate may be selected such that aquantity of the organic reactant may be flowed into the reaction chamberduring a cycle of the deposition process to facilitate metal surfacereduction or protecting the metal surface from being oxidized orfacilitate increased selectivity.

Embodiments of the invention may be directed to selectively depositmetal or semi-metal oxide film using an organic reactant source onmicrometer-scale (or smaller) features during integrated circuitfabrication. For example, process flows described herein may be used tomanufacture features having a size less than 100 micrometers, less than1 micrometer, or less than 200 nm. In the case of selective depositionof tungsten on copper for interconnects, the size of the feature or linewidth may be less than 1 micrometer, less than 200 nm, less than 100 nm,or less than 50 nm. One of ordinary skill in the art may recognize thatselective deposition on larger features and in other contexts ispossible using the disclosed methods.

As mentioned above, the selectivity may be expressed as the ratio ofmaterial formed on the first surface (A) minus the amount of materialformed on the second surface (B) to amount of material formed on thefirst surface (A) (i.e., selectivity can be given as a percentagecalculated by [(deposition on first surface)−(deposition on secondsurface)]/(deposition on the first surface) or [(A−B)/A]). Preferably,the selectivity is above about 70%, above about 80%, more preferablyabove 90%, even more preferably above 95%, or most preferably about100%. In some cases, selectivity above 80% may be acceptable for certainapplications. In some cases, selectivity above 50% may be acceptable forcertain applications. In some embodiments, the deposition temperaturemay be selected such that the selectivity is above about 90%. In someembodiments, the deposition temperature may be selected such that aselectivity of about 100% is achieved.

In some embodiments, the thickness of the film that is selectivelydeposited may be less than about 100 nm, less than about 50 nm, about 25nm or less than about 10 nm, in some embodiments, from about 0.5 nm toabout 100 nm or from about 1 nm to about 50 nm. However, in some cases adesired level of selectivity, for example more than 50%, more preferablymore than 80%, is achieved with the thicknesses of the selectivelydeposited film being over about 2.5 nm , about 5 nm, over about 10 nm,over about 25 nm or over about 50 nm.

FIG. 1 illustrates a semiconductor device 100 in accordance with atleast one embodiment of the invention. The semiconductor device 100 maycomprise a substrate 110, a metal layer 120, and a dielectric layer 130.The substrate 110 may comprise a material such as silicon or silicongermanium. The metal layer 120 may comprise a material such as tungsten,cobalt or copper. The dielectric layer 130 may comprise a material suchas silicon dioxide, or various low-k dielectric layers.

The substrate may comprise various types of materials. Whenmanufacturing integrated circuits, the substrate typically comprises anumber of thin films with varying chemical and physical properties. Forexample and without limitation, the substrate may comprise asilicon-containing layer and a metal layer. In some embodiments, thesubstrate can comprise metal carbide. In some embodiments, the substratecan comprise a conductive oxide.

In at least one embodiment, the substrate may have a first surfacecomprising a metal, referred to herein as the first metal surface orfirst metallic surface. The first surface may be essentially anelemental metal, such as Cu or Co. In other embodiments, the firstsurface may comprise a metal nitride or a transition metal. Thetransition metal may be selected from the group: Ti, V, Cr, Mn, Nb, Mo,Ru, Rh, Pd, Ag, Au, Hf, Ta, W, Re, Os, Ir, and Pt. In some embodiments,the first surface may comprise a noble metal, such as Au, Pt, Ir, Pd,Os, Ag, Re, Rh, and Ru, for example. In other embodiments, the metal orsemi-metal film deposited using one or more organic reactants as oxygensource may be selectively deposited on a metal oxide surface relative toother surfaces, where the metal oxide surface may be, for example aWO_(x), HfO_(x), TiO_(x), AlO_(x), or ZrO_(x) surface. In someembodiments, a metal oxide surface may be an oxidized surface of ametallic material.

In at least one embodiment, the substrate may have a second surfacewhich is preferably a silicon containing surface, referred to herein asthe second silicon containing surface or second surface comprisingsilicon. In some embodiments, the silicon containing surface maycomprise, for example, SiO₂ or surface comprising Si—O bonds. In someembodiments, the second surface may comprise silicon oxide, siliconnitride, silicon carbide, silicon oxynitride, silicon dioxide, ormixtures thereof. In some embodiments, the material comprising thesecond surface may be a porous material. In some embodiments, the porousmaterial may contain pores which are connected to each other, while inother embodiments, the pores are not connected to each other. In someembodiments, the second surface may comprise a low-k material, definedas an insulator with a dielectric value below about 4.0. In someembodiments, the dielectric value of the low-k material may be belowabout 3.5, below about 3.0, below about 2.5, or below about 2.3.

FIG. 2 illustrates the semiconductor device 100 in accordance with atleast one embodiment of the invention. The semiconductor device 100includes a metal oxide 140 deposited on the dielectric layer 130. Metaloxides that may be formed include a germanium, transition metal oxide ormetal oxide films, such as germanium oxide (GeO₂), titanium oxide(TiO₂), hafnium oxide (HfO₂), or zirconium oxide (ZrO₂), for example. Insome embodiments the metal oxide film is not silicon dioxide film and/orin some embodiments the metal oxide film does not comprise silicon. Forsimplicity reasons germanium here in is considered to be a metal. Insome embodiments the germanium oxide layer comprises Ge—O bonds and doesnot comprise substantial amounts of metals.

FIG. 3 illustrates the semiconductor device 100 in accordance with atleast one embodiment of the invention. The semiconductor device 100includes a metal oxide 140 deposited on the metal layer 120. Metaloxides that may be formed include a germanium oxide (GeO₂), titaniumoxide (TiO₂), hafnium oxide (HfO₂), or zirconium oxide (ZrO₂), forexample.

Many of the metal oxides that are listed above may be deposited usingwater as a precursor, but processes in accordance with the presentinvention may avoid the issues associated using water as a precursor.FIG. 4 illustrates an ALD method in accordance with at least oneembodiment of the invention. The ALD method 200 may deposit a metaloxide film on either the dielectric layer or the metal layer. It shouldbe noted that although referred to an ALD method, such methods asdescribed herein can be a cyclic or sequential CVD process, such as aCVD process in which gas-phase reactions are avoided.

The ALD method 200 includes a step of pulsing a metal or semi-metalprecursor 210. Metal or semi-metal precursors that may be used in step210 may include germanium alkylamide, such as germanium dialkylamine,like (Ge(NMe₂)₄). In some embodiments the metal or semi-metal precursoris a metal halide, such as transition metal halide or for example,aluminum halide, such as aluminum chloride. In some embodiments themetal or semi-metal precursor comprises halide, such as chlorine. Insome embodiments the metal or semi-metal precursor is a metal chloride,such as transition metal chloride, such as TiCl₄, HfCl₄ or ZrCl₄. Insome embodiments the metal or semi-metal precursor is a metalorganicprecursor, such as metalorganic precursor comprising transition metal.In some embodiments the metal or semi-metal precursor is a metalalkylamine precursor, such as Ti(NEtMe)₄, Hf(NEtMe)₄, or Zr(NEtMe)₄. Insome embodiments the metal or semi-metal precursor is organometallicprecursor, such as alkylaluminum compounds, for exampletrimethylaluminum (TMA), or such as cyclopentadienyl compounds of Ti, Hfor Zr, for example, (pentamethylcyclopentadienyl)trimethoxytitanium(Me₅Cp)Ti(OMe)₃, bis(methylcyclopentadienyl)methoxymethylhafnium(MeCp)₂Hf(OMe)Me or tris(dimethylamino)cyclopentadienylzirconiumCpZr(NMe₂)₃. The pulse step 210 may take place for a time durationranging between 0.01 and 60 seconds, from about 0.1 to about 30 secondsor from about 0.2 to about 10 seconds at temperatures ranging betweenabout 0 to about 750° C., from about 50 to about 500° C., or from about150 and 350° C. Step 210 may then be followed by a purge step 220, whichwould remove any excess metal or semi-metal precursors.

A number of different Ge precursors can be used in the depositionprocesses. In some embodiments the Ge precursor is tetravalent (i.e. Gehas an oxidation state of +IV). In some embodiments, the Ge precursor isnot divalent (i.e., Ge has an oxidation state of +II). In someembodiments, the Ge precursor may comprise at least one alkoxide ligand.In some embodiments, the Ge precursor may comprise at least one amine oralkylamine ligand. In some embodiments the Ge precursor is ametal-organic or organometallic compound. In some embodiments the Geprecursor comprises at least one halide ligand. In some embodiments theGe precursor does not comprise a halide ligand.

For example, Ge precursors from formulas VIII-X below may be used insome embodiments:

Ge(NR^(I)R^(II))₄   (VIII)

wherein R^(I) can be independently selected from the group consisting ofhydrogen, alkyl and substituted alkyl; and R^(II) can be independentlyselected from the group consisting of alkyl and substituted alkyl;

Ge(NR^(I)R^(II))₄   (IX)

wherein the x is an integer from 1 to 4; R^(I) can be independentlyselected from the group consisting of hydrogen, alkyl and substitutedalkyl; and R^(II) can be independently selected from the groupconsisting of alkyl and substituted alkyl; A can be independentlyselected from the group consisting of alkyl, alkoxides, alkylsilyls,alkyl, substituted alkyl, alkylamines, halide, and hydrogen;

Ge_(n)(NR^(I)R^(II))_(2n+2)   (X)

wherein the n is an integer from 1 to 3; R^(I) can be independentlyselected from the group consisting of hydrogen, alkyl and substitutedalkyl; and R^(II) can be independently selected from the groupconsisting of alkyl and substituted alkyl.

The ALD method 200 may also include a step of pulsing an organicreactant 230. Organic reactant may include formic acid (HCOOH), anysimple carboxylic acid, or any precursor that might decompose into CO,CO₂, or any other by-product species, and H₂O, or any other organicprecursor noted herein. For example, a step 230 pulsing formic acid(and/or another organic reactant) may use a purity of organic reactant,such as formic acid and/or other organic reactant of at least 90%, morepreferably at least 95%, and more preferably at least 98%, in order toobtain a properly deposited layer. The pulse step 230 may take place fora time duration ranging between 0.01 and 60 seconds, from about 0.1 toabout 30 seconds or from about 0.2 to about 10 seconds at a temperaturerange ranging between about 0 to about 750° C., from about 50 to about500 C or from about 150 and 350° C. Step 230 may then be followed by apurge step 240, which would remove any excess organic reactant(s). Thesteps of the ALD method 200 may be repeated to form an oxide layer of adesired thickness. In some embodiments, the purge step of the organicreactant(s) may be less than about 10 seconds, less than about 5seconds, less than about 2 seconds, less than about 1 second, less thanabout 0.5 seconds while still retaining selective deposition. In someembodiments, the same degree of selectivity may not be retained if awater or other oxygen source than an organic reactant is used. While theexemplary pulse and purge times mentioned above may be applicable tomany different types of reactors, single wafer, or mini-batch reactors,pulse and purge times may be higher in case of batch reactors with highsurface areas. Any of the purge steps as discussed herein can use aninert gas, such nitrogen and/or a noble gas, such as argon and/orhelium.

The ALD method 200 enables selective deposition on a substratecomprising at least two different surfaces, for example, a first surfacecomprising metal, such as Cu, and second surface comprising silicon,such as silicon dioxide or low-k material. As a result, for example, ametal oxide film can be formed on the dielectric material, while themetal surface can remain uncovered or vice versa. In addition, there maybe more efficient purging of the carboxylic acid or other organicreactant due to its lower polarity in comparison to water. The use ofozone (O₃) or oxygen plasma or oxygen atoms or oxygen radicals may beavoided due to its tendency to oxidize metals or metallic materials orsurfaces easily as well as destroying the selectivity. In someembodiments, plasma may not be used in the deposition process. Althoughdescribed in connection with ALD processing, method 200 can similarly beperformed using sequential/cyclic CVD.

In some embodiments, the selective deposited film using organic reactantmay have a growth rate of less than about 5 Å/cycle, less than about 2.5Å/cycle, less than about 1.5 Å/cycle or less than about 1.0 Å/cycle. Inother embodiments the selective deposited film using organic reactanthas a growth rate from about 0.01 to about 5 Å/cycle, from about 0.05 toabout 2.5 Å/cycle or from about 0.1 to about 2 Å/cycle.

FIG. 5 illustrates an ALD (or sequential/cyclic CVD) method inaccordance with at least one embodiment of the invention. The ALD method300 may deposit a metal oxide film on either a dielectric layer or ametal layer.

The ALD method 300 may include a step of pulsing an organic reactant310. Organic reactants may include formic acid (HCOOH), any simplecarboxylic acid, or any precursor that might decompose into CO, CO₂, orany other by-product species and H₂O, or other organic reactant asdescribed herein. For example, a step 310 pulsing formic acid or otherorganic reactant may use a purity of formic acid or other organicreactant of at least 90%, at least 95%, and more preferably at least 98%in order to obtain a properly deposited layer. The pulse step 310 maytake place for a time duration ranging between 0.01 and 60 seconds, fromabout 0.1 to about 30 seconds, or from about 0.2 to about 10 seconds attemperatures ranging between 0 and 750° C., between 50 and 500° C., orbetween 150 and 350° C. Step 310 may then be followed by a purge step320, which would remove any excess organic reactants.

The steps of the ALD method 300 may be repeated to form an oxide layerof a desired thickness. In some embodiments, the purge step of theorganic reactant may be less than about 10 seconds, less than about 5seconds, less than about 2 seconds, less than about 1 second, less thanabout 0.5 seconds while still retaining selective deposition. In someembodiments, the same degree of selectivity may not be retained if awater or other oxygen source than the organic reactant is used. Whilethe exemplary pulse and purge times mentioned above may be applicable tomany different types of reactors, single wafer, or mini-batch reactors,pulse and purge times may be higher in case of batch reactors with highsurface areas.

The ALD method 300 includes a step of pulsing a metal or semi-metalprecursor 330. Metal or semi-metal precursors that may be used in step330 may include germanium alkylamide, such as germanium dialkylaminelike (Ge(NMe₂)₄), for example. The pulse step 330 may take place for atime duration ranging between 0.01 and 60 seconds, from about 0.1 toabout 30 seconds, or from about 0.2 to about 10 seconds at temperaturesranging between about 0 to about 750° C., from about 50 to about 500°C., or from about 150 and 350° C. Step 330 may then be followed by apurge step 340, which would remove any excess metal or semi-metalprecursors. The steps of the ALD method 300 may be repeated to form anoxide layer of a desired thickness.

The ALD method 300 enables selective deposition on a substratecomprising at least two different surfaces, for example, a first surfacecomprising metal, such as Cu, and second surface comprising silicon,such as silicon dioxide or low-k silicon. As a result, for example, ametal oxide film can be formed on the dielectric, while the metalsurface can remain uncovered or vice versa. In addition, there may bemore efficient purging of the carboxylic acid reactant due to its lowerpolarity in comparison to water. The use of ozone (O₃), oxygen plasma,oxygen atoms, or oxygen radicals may be avoided due to its tendency tooxidize metals or metallic materials or surfaces easily as well asdestroying the selectivity. In some embodiments, plasma may not be usedin the deposition process.

The ALD method 300 may modify the metal surface of the substrate. Forexample, the carboxylic acid (or other organic reactant) may reduce ametallic surface or elemental metal, such as copper oxide (CuO), surfaceto metallic or elemental metal, such as elemental copper. In addition,the carboxylic acid may remove any remaining passivation layer on themetal surface, such as benzotriazole (BTA). Both of these effects arebenefits because removal of the passivation layer or reduction tostraight copper may both be capable of enabling selective growth.Similar to method 200, method 300 may be a cyclic CVC process, ratherthan an ALD process.

Quality of the metal oxide layer deposited through either ALD method 200or ALD method 300 may be judged by a selectivity of a surface of themetal oxide layer. For example, the selectivity may be quantified by athickness of the metal oxide layer in relation to thickness deposited onthe desired layer.

The particular implementations shown and described are illustrative ofthe invention and its best mode and are not intended to otherwise limitthe scope of the aspects and implementations in any way. Indeed, for thesake of brevity, conventional manufacturing, connection, preparation,and other functional aspects of the system may not be described indetail. Furthermore, the connecting lines shown in the various figuresare intended to represent exemplary functional relationships and/orphysical couplings between the various elements. Many alternative oradditional functional relationship or physical connections may bepresent in the practical system, and/or may be absent in someembodiments.

It is to be understood that the configurations and/or approachesdescribed herein are exemplary in nature, and that these specificembodiments or examples are not to be considered in a limiting sense,because numerous variations are possible. The specific routines ormethods described herein may represent one or more of any number ofprocessing strategies. Thus, the various acts illustrated may beperformed in the sequence illustrated, in other sequences, or omitted insome cases.

The subject matter of the present disclosure includes all novel andnonobvious combinations and subcombinations of the various processes,systems, and configurations, and other features, functions, acts, and/orproperties disclosed herein, as well as any and all equivalents thereof.

We claim:
 1. A method of selectively forming a metal oxide comprising:providing a substrate comprising a dielectric layer and a layercomprising metal for processing in a reaction chamber; exposing thesubstrate to a metal or semi-metal precursor; exposing the substrate toone or more of a first purging step and a vacuum; exposing the substrateto an organic reactant; and exposing the substrate to one or more of asecond purging step and the vacuum; wherein a reaction between the metalor semi-metal precursor and the organic reactant selectively forms ametal oxide on the dielectric layer, wherein a selectivity of formationof the metal oxide layer on the dielectric layer, as defined as a ratioof a first amount formed on the dielectric layer minus a second amountformed on the layer comprising metal to the first amount, is greaterthan 50%, and wherein the metal or semi-metal precursor comprises one ormore of an alkoxide ligand, an amine ligand, and an alkylamine ligand.2. The method of claim 1, wherein exposing the substrate to the organicreactant comprises reducing metallic materials in the layer comprisingmetal to elemental metal.
 3. The method of claim 2, wherein reducing themetallic materials in the layer comprising metal to elemental metalfacilitates the selectivity.
 4. The method of claim 1, wherein exposingthe substrate to the organic reactant comprises removing passivationfrom the layer comprising metal.
 5. The method of claim 1, wherein theorganic reactant comprises an aldehyde.
 6. The method of claim 5,wherein the aldehyde comprises a chemical formula represented by:OHC—R—CHO wherein R is a linear or branched C1-C20 saturated orunsaturated hydrocarbon.
 7. The method of claim 1, wherein the metal orsemi-metal precursor comprises germanium.
 8. The method of claim 1,wherein the organic reactant comprises a carboxylic acid.
 9. The methodof claim 1, wherein the organic reactant decomposes into two or morereactive components.
 10. The method of claim 1, wherein the organicreactant is stored in a liquid phase.
 11. The method of claim 1, whereinthe organic reactant is stored in a gas bubbler.
 12. The method of claim1, wherein the metal oxide layer comprising one or more of germaniumoxide, titanium oxide, and hafnium oxide.
 13. The method of claim 1,wherein exposing the substrate to the organic reactant comprisesdecomposing the organic reactant to carbon monoxide and hydrogen gas.14. The method of claim 13, wherein the method does not include directlysupplying hydrogen gas to reaction chamber.
 15. A method of selectivelyforming a metal oxide comprising: providing a substrate comprising adielectric layer and a layer comprising metal for processing in areaction chamber; exposing the substrate to a metal or semi-metalprecursor; exposing the substrate to one or more of a first purging stepand a vacuum; exposing the substrate to an organic reactant; andexposing the substrate to one or more of a second purging step and thevacuum; wherein a reaction between the metal or semi-metal precursor andthe organic reactant selectively forms a metal oxide layer on thedielectric layer, wherein a selectivity of formation of the metal oxidelayer on the dielectric layer, as defined as a ratio of a first amountformed on the dielectric layer minus a second amount formed on the layercomprising metal to the first amount, is greater than 50%, wherein themetal or semi-metal precursor comprises one or more of an alkoxideligand, an amine ligand, and an alkylamine ligand, and wherein exposingthe substrate to the organic reactant comprises reducing metallicmaterials in the layer comprising metal.
 16. The method of claim 15,wherein exposing the substrate to the organic reactant comprisesremoving passivation from the layer comprising metal.
 17. The method ofclaim 15, wherein the layer comprising metal consists essentially of anelemental metal.
 18. The method of claim 15, wherein the organicreactant comprises an aldehyde.
 19. The method of claim 15, wherein theorganic reactant comprises a carboxylic acid.
 20. A semiconductor deviceformed using the method of claim 1.